We examined how DOM composition varied across 21 locations within a river network using optical measurements of DOM composition collected at weekly to monthly intervals to determine how DOM composition varies spatially and temporally throughout a river network.We found that DOM became more homogenous as water moves downstream in a river network, but temporal variability in DOM composition behaved similarly regardless of position in the river network.Despite the homogeneity of DOM composition in the mainstem of the Lamprey river biodegradable DOC (%BDOC in 7 days) was variable across space and time.Our results suggest that incorporating optical measurements of DOM composition into regular water quality monitoring protocols can provide important information about DOM quality.Taken together with previous research our results demonstrate that DOM composition varies with position in a river network across biomes and across land use and land cover gradients.

Studying the relationship between discharge and stream solutes, particularly during storm events, can provide valuable insight on the sources and transport pathways for solute delivery to streams. The NH EPSCoR Aquatic Sensor Network measures a wide array of water quality parameters on a near-continuous basis at 10 sites across NH.There are 8 headwater sites that span a range of land use and drain to two mainstem sites located in the Lamprey and Merrimack Rivers. This sensor network provides an unparalleled opportunity to understand the regional coherence in solute response to storms across seasons and over multiple years.The suburban, urban and agricultural headwater sites exhibited an overall pattern of diluting nitrate concentration and conductance during storms, but the response in the forested headwater and mainstem sites was more variable.The response of FDOM, a proxy for organic carbon, often differed from the response of nitrate and conductance.Here we will examine these relationships in more detail to advance our understanding of sources and transport pathways for carbon, nitrogen and salt.

Watershed nitrogen exports are often dominated by dissolved organic nitrogen (DON); yet, little is known about the role ambient DON plays in ecosystems. As an organic nutrient, DON may serve as either an energy source or as a nutrient source. One hypothesized control on DON is nitrate (NO3-) availability. Here we examine the interaction of NO3- and DON in streams across temperate forests, tropical rainforests, and Mediterranean and taiga biomes. Experimental streams also drain contrasting Critical Zones which provide gradients of vegetation, soil type and lithology (e.g. volcaniclastic, granitic, ultramafic, Siberian Traps Flood Basalt) in which to explore how the architecture of the Critical Zone affects microbial biogeochemical reactions. Streams ranged in background dissolved organic carbon (DOC) concentration (1-50 mg C/L) and DOC: NO3- ratios (10-2000). We performed a series of ecosystem-scale NO3- additions in multiple streams within each environment and measured the change in DON concentration. Results demonstrate that there is considerable temporal and spatial variation across systems with DON both increasing and decreasing in response to NO3- addition. Ecologically this suggests that DON can serve as both a nutrient source and an energy source to aquatic microbial communities. In contrast, DOC concentrations rarely changed in response to NO3- additions suggesting that the N-rich fraction of the ambient dissolved organic matter pool is more bioreactive than the C-rich fraction. Contrasting responses of the DON and DOC pools indicate different mechanisms controlling their respective cycling. It is likely that DON plays a larger role in ecosystems than previously recognized.

A longer vernal window: the role of winter coldness and snowpack in driving spring transitions and lags – Alexandra Contosta, Post-Doctoral Research Associate, UNH

Climate change is altering the timing and duration of the vernal window, a period that marks the end of winter and; the start of the growing season when rapid transitions in ecosystem energy, water, nutrient, and carbon dynamics; take place. Research on this period typically captures only a portion of the ecosystem in transition and focuses largely; on the dates by which the system wakes up. Previous work has not addressed lags between transitions that represent; delays in energy, water, nutrient, and carbon flows. The objectives of this study were to establish the sequence of; physical and biogeochemical transitions and lags during the vernal window period and to understand how climate; change may alter them. We synthesized observations from a statewide sensor network in New Hampshire, USA, that; concurrently monitored climate, snow, soils, and streams over a three-year period and supplemented these observations; with climate reanalysis data, snow data assimilation model output, and satellite spectral data. We found that; some of the transitions that occurred within the vernal window were sequential, with air temperatures warming prior; to snow melt, which preceded forest canopy closure. Other transitions were simultaneous with one another and had; zero-length lags, such as snowpack disappearance, rapid soil warming, and peak stream discharge. We modeled lags; as a function of both winter coldness and snow depth, both of which are expected to decline with climate change.; Warmer winters with less snow resulted in longer lags and a more protracted vernal window. This lengthening of; individual lags and of the entire vernal window carries important consequences for the thermodynamics and biogeochemistry; of ecosystems, both during the winter-to-spring transition and throughout the rest of the year.

Synopsis of 23 years of water quality monitoring and other volunteer efforts will be presented.

Projections of paired water temperature and chloride as stressors to aquatic species in New Hampshire – Shan Zuidema, Research Scientist, Water Systems Analysis Group, UNH

The historic and continued introduction of road salt to watersheds and carbon to our atmosphere pose dual threats to aquatic ecosystems.Sodium chloride introduced to watersheds as roadway deicer can take decades to travel through a catchment, resulting in high summer-time concentrations considered harmful to aquatic organisms.Atmospheric warming in New Hampshire is expected to lead to dramatic increases in stream temperature relative to 20th century averages.We utilize a set of land cover and climate scenarios to estimate 21st century regimes of stream temperature and chloride concentration throughout the Merrimack and Piscataqua River watersheds, and compare to thresholds indicative of ecosystem harm.Accounting for fairly wide uncertainties in groundwater transit time and historic loading, water temperature impacts increase more under high emission pathways than road salt impacts increase under high development pathways.However, reducing road salting to recommended values would likely be protective of many aquatic species in most years.Model results such as these can help us determine management and interventions to help support robust aquatic ecosystems under future conditions.

Fecal bacteria have a significant impact on downstream water quality. Removal of fecal bacteria in river systems potentially attenuates downstream impairments and would represent an important ecosystem service. The goal of this study is to understand the ecosystem service of fecal bacteria removal at the river network scale across hydrologic conditions. I developed a module for routing fecal indicator bacteria (FIB) through river networks in the Framework for Aquatic Modeling of the Earth System (FrAMES) model to understand the fate and transport of E. coli, which is the freshwater indicator for fecal contamination. E. coli loading from land and aquatic removal in both water column and hyporheic zone was simulated for every river grid cell throughout the river network. This study found that the hyporheic zone is important in removing E. coli. The water column and the hyporheic zone removed approximately 15% and 50% of E. coli input, respectively, in Lamprey River watershed during the summer period. The water column and the hyporheic zone removed approximately 10-30% and 30-50% of E. coli input, respectively, in other study watersheds during the summer period. Hydrology has the most significant impact to determine network-scale E. coli removal. Low-frequency but high-magnitude hydrologic events mobilize a disproportionate amount of E. coli. The attenuation efficiency of river networks decreases as the flow increases, but remains relatively high at higher flows common during critical summer periods. This study found that the ecosystem service of E. coli removal reduces E. coli levels at critical downstream water bodies, such as recreational lakes and estuaries. Shellfish and beach managers should prioritize mitigation of small watersheds with sources near the basin mouth, since their removal efficiency is limited. These results have important implications for managing bacteria contamination.

In May of 2016, the UNH/Durham Water System (UDWS) put the Spruce Hole Groundwater Source & Artificial Recharge Facility on line.The facility consists of a new gravel-packed well and two artificial recharge basins which receive water from an existing pumping station with an intake in the Lamprey River.In addition to adding a second groundwater supply to the system, these facilities allow the UDWS to withdraw water from the Lamprey River during periods of high flow and store it in the aquifer for later pumping during low flow periods when there are withdrawal restrictions on the Lamprey River.This presentation will discuss the development, design and construction of the new gravel packed well and artificial recharge basins at the Spruce Hole Aquifer as well some of the recent operating history since the facility went on line.

Reintroducing large wood into headwater streams for habitat development and nutrient retention – Joel DeStasio, NH Field Manager, Trout Unlimited

Beginning in 2014, Trout Unlimited has been working with the USDA Natural Resource Conservation Service (NRCS) to monitor and restore instream fish habitat at 23 NRCS Wetlands Reserve Program (WRP) conservation easements in southern New Hampshire. The goal of these restorations is to reintroduce large wood into sections of stream where the natural recruitment of large instream wood becomes limited. Our restoration projects aim to improve instream habitat & structure for fish and also influence spawning potential by improving sediment transport, pool/riffle runs, and stream cover. Throughout the summer seasons, streams at each easement have had water parameters recorded and samples collected to analyze nutrient content. This has allowed us to establish the current water quality & habitability of streams for each easement. This information will serve to better identify the value of large wood additions in smaller order streams and understand the intrinsic value instream wood has on restoring fish habitat.

Poster Session

Soils contaminated with lead arsenate, collected from a historic apple orchard, were evaluated to determine if the residential development of the property would affect the mobility of lead or arsenic as a result of the application of various lawncare/homecare treatments expected on residential properties.Four columns were constructed to evaluate the effects of 3 residential treatment solutions: a salt deicing solution (50mM NaCl), a nitrate fertilizer (1.6mM KNO3) and a phosphate fertilizer (1.05mM K2HPO4) in comparison to a control (simulated rainwater).The collected soils were eluted with alternating influent solutions of either the respective treatment solution or synthetic rain water for a simulated 6yr period (75 bed volumes).Metals analyses demonstrated that elevated levels of lead were released beyond the control for all 3 treatments.Elevated levels of arsenic were observed with the phosphate treatment; with similar and lower levels in the salt and nitrate fertilizer treatments, respectively.These findings may have impacts on the environmental implications of residential development of historic apple orchards or any farmland historically treated with inorganic pesticides.